I don't think Spotify was created with deaf people in mind.
That would be the problem.
how would they charge people who can hear, but offer the service for free to those who can't?
This sounds like an engineering problem. Account types, customer service, some kind of medical qualification proving it, I don't know.
They could also just... not separate lyrics from the free-tier at all.
I mean, painfully missing from this discussion is that hiding the lyrics of the song you're listening to, which they definitely have, behind a paywall is... absolutely bizarre.
To my ears, this is like finding out Spotify's new free-tier model limits song listens to exactly 2 minutes, and if the song is longer than that, "well, you can listen to the whole thing with a new Premium subscription!" Yeah, I guess I could, huh. God forbid we have anything nice in this country.